Truss girders of round steel



y 1962 o. NERATH 3,032,153

TRUSS GIRDERS 0F ROUND STEEL Filed June 24, 1957 2 Sheets-Sheet 1 7b 5Fig. 2b 6 Fig. 2c

INVENTOR Orwell HER/UK Zww y 1962 o. NERATH 3,032,153

TRUSS GIRDERS OF ROUND STEEL Filed June 24, 1957 2 Sheets-Sheet 2INVENTOR OTMHR Ni-R 6TH lay/16 1 GIOEN'V 3,032,153 TRUSS GIRDERS OFROUND STEEL Otmar N erath, Loreley Strasse 12, Frankfurt am Main Hochst,Germany Filed June 24, 1957, Ser. No. 667,611 Claims priority,application Germany June 26, 1956 Claims. (Cl. 18937) The inventionconcerns a truss girder of round steel comprising a compression chordand a stiffening truss projecting from the compression chord at one sidethereof.

Girders of round steel are already known. Their loadbearing capacity andresistance to buckling forces exceeds that of triangular lattice girdersor other spacial trusses. The known girder constructions of round steelrequire a comparatively high quality of material and their manufactureis time-consuming. This is especially due to the fact that numerouswelding spots are required for the known girders of round steel. It,therefore, is the object of the present invention to fully utilize themost advantageous properties of round steel, to attain constructions forwhich essentially fewer welding spots for connection of the buildingelements will be required without deteriorating the static relations.

According to the invention this goal is achieved by connecting to thecompression chords of a simple supporting truss a stiffening trussprojecting from the vertical plane defined by the chords at a right,acute or obtuse angle. The stiffening truss serves for the purpose ofsecuring the compression chords against buckling. The trusses andbracings, preferably consisting of round steel, may be weldedelectrically. Beside round steel other rod steels, for instance squaresteel, are also suitable. The stiff truss girder of round steel isespecially suitable for roof constructions, such as roofs of industrialbuildings and dwelling houses of all kinds and with every kind ofroofing, for girders on two supports as well as for purlins, pipebridges, masts, such as line masts for electrically operated railroadsand for overhead lines, and also for ceiling and form supports forconcrete work.

When using the truss girder according to the invention as roof purlinsthe arrangement of the stiffening truss has the special advantage thatthe thrust of the roof covering from the ridge to the eaves can be takenup entirely by the stiffening truss. The stiffening truss then acts asthe lower span of the upper chord of the supporting truss of the purlinin the direction of the inclined plane of the roof to the eaves.Therefore, very simple, widely spanned purlins can be made withoutadditional suspension of the ridge of a roof.

In case of purlins it is suitable to connect the stiffening trussacute-angled. This renders it possible to raise wooden purlins on thetop truss as required, on which the roofing, such as corrugated sheets,wooden covering or roof laths for tiles, can be put up.

A special advantage when using the truss girder according to theinvention is that, for instance, the roof constructions can take up windpressures and other side loads by means of a suitable stiffening truss,so that the greatest part of the otherwise requisite framings can besaved. For this reason the stiffening truss can be welded on in variouswidths corresponding to the respective requirements.

In the case of roof cutting and hip constructions the side truss can beadapted in a suitable acute or obtuse angle.

If the stiffening truss is afiixed at an acute angle then the top trussof the main girder can be made free for the connection of purlins of thesame system. The purlins can then be directly connected to the top trussof the supatent porting truss without projecting into the stiifeningtruss. This is especially advantageous in the case of continuouspurlins. Rigid connections of the chord members is necessary for thesewhen they are continuous so that the latter can be connected with eachother without any difficulty.

If a buckling stress appears in the bottom chord a stiffening truss canbe welded on in any desired direction to take up these forces.

A further advantage of the truss girder according to the invention is tobe seen in the fact that it can be easily manufactured. Thus the loosetop chord of the supporting truss can be connected with the stiffeningtruss on a simple support. And after this has taken place one canassemble the stiffening truss with the supporting truss after it hasbeen set up. One can also accomplish this inversely.

The diagonal rods or lattice means of the supporting truss can be weldedto the chord members as individual members or as a building elementbent. in zig-zag form. Electricarc welding or electric resistancewelding can be used for instance spot welding machines. These simpleworking operations render it possible to assemble the truss girders onthe spot where they are needed for the building. The structural elementscan be prepared in the factory so that the materials can be transportedto the building site cut to fit. The welding can take place on portablecontrivances which are brought to the building site. Thus the expensivetransportation of the finished truss girders, which take up a great dealof space, is eliminated. All the advantages mentioned bring aboutconsiderable manufacturing economies compared to other truss girders.

It may be necessary to secure the. stiffening truss against sagging ofthe outside chord. For this purpose it is practical that rods be weldedat intervals between the outside chord of the stiffening truss and thelower chord of the supporting truss, thus propping the stiffening trussto the lower chord of the supporting truss.

The invention is illustrated schematically in some exemplary embodimentsshown in the accompanying drawing wherein FIG. 1 is a side view of thetruss girder, whose individual trusses are welded to each otherelectrically with the chords at right angles,

FIG. 1a is a cross section according to the line A-A of FIG. 1 withpropping,

FIG. lb is a top view of the truss girder according to FIG. 1,

FIG. 1c is an end view of the truss girder according to FIG. 1 in thedirection of its longitudinal axis, without propping,

FIG. 2 is a side view of the truss girder wherein the bracing of thestiffening truss is Welded directly to the upper compression chord,

FIG. 2a is a cross section according to the line B-B of FIG. 2 withpropping,

FIG. 2b is a top view of the truss girder according to PEG. 2,

FIG. 20 is an end view of the truss girder according to FIG. 2 in thedirection of its longitudinal axis, without propping,

H68. 3 and 4 show the stiffening truss connected at an acute and anobtuse angle, respectively,

FIGS. 5, 6 and 7 show the trusses connected with each otherrectangularly or at an obtuse or acute-angle at the lower chord whichserves as compression chord, with suspension of the stiffening trussfrom the upper chord serving as tension chord.

In the drawings the upper chord of the truss girder 11 is designatedwith 1, which represents the compression a chord according to FIGURES 1to 4. 2 is the lower chord of the supporting truss which, in the case ofthe FIGURES to 7, is the compression chord. The diagonal rods 3 form alattice connecting the two chords with each other in the plane of thesupporting truss. Propping rods 4 serve for propping the stiffeningtruss 12 against the lower chord 2 of the supporting truss according toFIGURES 1 to 4, whilst the stiflening truss 12 is connected to the upperchord 1 of the supporting truss by the propping rods 4 according toFIGURES 5 to 7.

The stiffening truss is formed by the outside chord 5 and the insidechord 8 between which a rigid connection is made by the diagonal rods 9in the plane of the stiffening truss as FIGURE 1b shows. According toFIGURE 21) the stiifening truss has only the outside chord 5, whilst thebracing is connected directly with the upper chord 1 of the supportingtruss at the inside.

End supports for the truss girder are designated with 70: and 7b. Forthis purpose the ends of the chords are bent, if, required, as is shownat 6 for the lower chord of the supporting truss in FIGURES 1 and 2, andfor the outer chord of the stiffening truss at 10 in FIG URE 111 Iclaim:

1. A truss girder made of round steel which comprises, in combination, acompression chord; a second chord parallel with and disposed in avertical plane common to said compression chord; lattice means rigidlyconnecting said chords in spaced relation; and a stiffening trusscomprising an outside chord of smaller diameter than the first-mentionedchords, said outside chord being spaced from and parallel with saidcompression chord, and means connecting said outside chord with saidcompression chord, said stiffening truss being in a plane enclosing anangle with said vertical plane.

2. The structure according to claim 1, wherein the plane of saidstiffening truss is disposed at right angles to said vertical plane.

3. The structure according to claim 1, wherein the plane of saidstiffening truss is disposed at an acute angle with respect to saidvertical plane.

4. The structure according to claim 1, wherein the plane of saidstittening truss is disposed at an obtuse angle with respect to saidvertical plane.

5. The structure according to claim 1, wherein said compression chord isdisposed above said second chord.

6. The structure according to claim 1, wherein said last mentioned meanscomprises an inside chord of smaller diameter than the compression chordand welded to said compression chord, and brace means welded to anddisposed between said inside chord and said outside chord.

7. Truss girder made of round steel comprising, in combination, threeparallel spaced chords, the first of said chords constituting acompression chord and the second of said chords being vertically alignedand in a common plane with said compression chord; lattice meansdisposed between and connected with said compression chord and saidsecond chord; and bracing means between said compression chord and thethird of said chords, said last mentioned chord being of smallerdiameter than the first and second chords, said third chord and saidcompression chord being in a common plane enclosing an angle with thevertical plane passing through said compression chord and said secondchord, said third chord and said bracing means constituting a stiffeningtruss.

References Cited in the file of this patent UNITED STATES PATENTS2,199,152 Edge et al. Apr. 30, 1940 FOREIGN PATENTS 545,594 Germany Mar.3, 1932 725,952 Great Britain Mar. 16, 1955 1,115,407 France Jan. 3,1956

